Stellar population synthesis for the spectra of blue compact galaxies

The method of population synthesis based on a grid of spectra, of star clus ters of different ages and metallicities is applied to four BCGs. Our resul ts indicate that the BCGs are old galaxies in which star formation occurs i n short spurts separated by long quiescent phases. There are unseen mass in BCGs, at least part of which is due to old populations. The amount of redd ening we found is significantly smaller than was found from the Balmer line ratio, and this can be explained by a model of foreground dust clumps, wit h different covering factors for the gas and stars.